pgsql: Update documentation table describing how shared memory is used

Log Message:
-----------
Update documentation table describing how shared memory is used by
various facilities.

Modified Files:
--------------
pgsql/doc/src/sgml:
runtime.sgml (r1.423 -> r1.424)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/runtime.sgml?r1=1.423&r2=1.424)